Re: [GHC] #14944: Compile speed regression

#14944: Compile speed regression -------------------------------------+------------------------------------- Reporter: br1 | Owner: dfeuer Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by dfeuer): The reason for the big version gap seems likely to be the fact that the code didn't compile at all under 7.8.4 or 7.10.3 without extra help. Here are the times I get: === 7.8.4 This version needed `-fcontext-stack=197` to compile. <> === 7.10.3 This version needed `-fcontext-stack=197` to compile. <> === 8.0.2 <> === 8.2.2 <> === 8.4.1 <> So there was a major regression from 7.8.4 to 7.10.3, another large one from 7.10.3 to 8.0.2, a large improvement from 8.0.2 to 8.2.2, and a smaller improvement from 8.2.2 to 8.4.1. I can verify that we're still running considerably slower, and allocating considerably more, than 7.8.4. FYI, while we no longer need `-fcontext-stack`, that's because the default limit has been raised or removed. It seems versions 8.0.2 through 8.4.1 need a reduction depth of 199. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14944#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler